DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
Texas Instruments TI-2550 II
| Date of introduction: | October 17, 1975 | Display technology: | Fluorescent |
| New price: | $49.95 | Display size: | 8 |
| Size: | 5.8" x 3.2" x
1.3" 147 x 81 x 32 mm3 |
||
| Weight: | 6.7 ounces, 190 grams | Serial No: | 085935 |
| Batteries: | BP2 | Date of manufacture: | wk 09 year 1976 |
| AC-Adapter: | AC9130, AC9130A | Origin of manufacture: | USA |
| Precision: | Integrated circuits: | TMS1071 (AP 7545) | |
| Memories: | Displays: | Itron FG95A1 | |
| Program steps: | Courtesy of: | Joerg Woerner | |
| Download manual: | 
(US: 2.8M Bytes) |
Its
product name gives you a first idea of this calculator: It is the successor of the
TI-2550, an early, wedge shaped basic calculator.
The housing used for the TI-2550 II is identically to the SR-16
II,
the difference is the keyplate and the underlying keyboard frame. The TI-2550 II
uses two sliding switches and a green Vacuum Fluorescent Display (VFD), a rare
combination in TI's calculator history.
The featured TI-2550 II with Date code 0976 LTA was manufactured in
February 1976 by Texas Instruments in
their Lubbock, TX facility. Dismantling this TI-2550 II reveals a design centered
centered around a TMS1071 single-chip calculator circuit connected to a 9-digit Itron FG95A1 display and powered by a BP2
battery pack with two AA-sized
rechargeable NiCd batteries.
This calculator was the first
use of the TMS1070, a modification of the original
TMS1000 LSI
MOS chip to directly interface with low-voltage VFDs up to 35 Volts. The TMS1001 found in the SR-16
used two external digit drivers for its Light Emitted Diode display.
This beautiful calculator was quickly replaced by the TI-2550
III,
a keyboard without a [+/-] key was not too useful. Ever wondered what's beneath
the empty position of the metalized keyplate? Yes, a fully functional [+/-] key
as featured with the Privileg 861 MD!
And the TI-2550 II is hiding even more functionality of the TMS1071 chip, learn
more about Characterization of Single-Chip Calculator Circuits with the
DCM-50A Platform.
A similar calculator chip was used with the innovative Canon MD-8
sporting a multi-line display.
Don't miss the TI-2550 II for the vision impaired people, the Schoenherr Braillotron 2550 II.
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, December 5, 2001. No reprints without written permission.